Mackie HR624 Repair

I love my Mackie HR624 monitors. Let’s face it, guys need speakers. Bi-amplified with 40w for the tweeter, 100w for the woofer, a passive radiator, selectable equalization for various speaker placements, phase correction, extremely flat response…what’s not to love? When I am enjoying some morning sitt’n time with a nice cup of joe in my hand, I like to crank them up (along with an BagEnd ELF subwoofer system…flat to below 18 cycles) and enjoy some tunes while checking email. I also use them for music and video production monitoring and they never fail to provide an accurate representation of the source material.

I bought these speakers maybe eight years ago and they have performed flawlessly…until a year or so ago that is. These speakers have a circuit that automatically turns on the amplifiers when an input signal is detected, and you can see the pilot light on the front panel come on when this happens. What happened was that one of the HR624s started having trouble turning on. The pilot light would flash on and off a few times before the speaker would finally stay on. This gradually got worse and worse, taking longer and longer to switch on, until a few weeks ago when the speaker would not turn on at all. OK time for some sitt’n time…with Google open on the iMac for some searching for others with similar problems. Sure enough I found a site which identified C65 as the culprit (that page no longer appears to be online unfortunately). C65 is a 63v 4.7uF electrolytic capacitor and I found an ebay dealer who sold me twenty five of them for about $8. OK time for some speaker surgery!

Note: I am going to describe how I repaired my own speaker since it might be of interest, but I am not encouraging you to try this yourself. These are the original 624s were long out of warranty. I used to work at a recording studio as a tech and have some limited experience making basic fixes to various kinds of audio equipment, but you could probably wreck your speaker if you did this incorrectly.

I did this work in our kitchen with a towel on the counter and the 624 on its face so I could easily access the amplifier module on the back (unit unplugged from AC of course). To remove the module I needed a Torx wrench. I don’t remember the exact size, but if you don’t have a Torx you can buy a set at a local hardware store.

Here is the speaker with the amp removed. That is the rear passive radiator you see.

When I got the module off I found capacitor C65 pretty quickly, but in order to get to the back of the circuit board where the solder traces are it looked like I’d have to completely disassemble the amplifier module. Not something I wanted to try. With nothing to lose since the speaker was broken anyway, I bent C65 back and forth until its leads broke off exposing the two small holes in the circuit board and the solder in each (you can click on my photos for larger versions)

location of C65new electrolytic capacitorscapacitor held in heatsink clamp

I then took one of the new capacitors I had purchased, trimmed the leads down to a reasonable length, clamped the leads in a heatsink (to avoid heat damage), and gingerly tinned the leads leaving a tiny blob of solder at the end of each. Finally I positioned the new capacitor leads so that they were resting on the solder/holes from the old capacitor. Since this was an electrolytic capacitor it was important to note the correct polarity. In the this case the negative side was facing the big toroidal transformer. An LED tactical flashlight positioned to shine into that area was critical to really see everything clearly (guys also need high-lumen tactical flashlights).

new capacitor in place

Finally using a fine tip Weller soldering iron I very carefully melted the solder in the holes along with the blobs on the leads. The result was a pretty decent soldering job with minimal dissassembly. After re-assembling the speaker I was happy to see that it worked perfectly! It now turns on and off exactly as it should and hopefully will last for several more years. Time to listen to some tunes. Sitt’n time.

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89 thoughts on “Mackie HR624 Repair”

I have the same problem. I sent it to sweetwater sound for a repair. They are idiots. They say there is nothing wrong. I am getting the speakers back and I will replace the cap as you did. Thanks for the info.

Thank you for this sir! I was on the verge of purchasing new monitors and ran across this page. My capacitors arrived in a day and I installed them no problem. (First time soldering) I successfully disassembled the amp. It was actually much easier than it appears to be. Anyway, after replacing C65 on both monitors, I was back in business. Thanks!

I really must express to you my gratitude and sincere thanks for having posted this DIY repair. My HR624’s recently failed due to an issue remarkably similar but somewhat different. The similarities were quite significant of course and your page was the only similar issue that I could uncover after several hours of exhaustive searching. This, of course, happened at the worst time. I’ve been working on a several thousand dollar recording/mastering session with a reputable local “prep” school and I’ve relied on these speakers for over 8 yrs. So, this DIY was my most cost effective and likely repair. Mackie no longer offers the PCB assembly and have become very non-forthcoming about possible fixes, also several authorized repair shops locally plain refuse to work on Mackie equipment anymore?!?!
Anyway, Thank you very much for your research and insight.
-Gabriel

Hi, This is the coolest page I have found in ages. I have these monitors and I have exactly the same problem. It’s so awesome that you shared this with the world. I am going to try it tomorrow. Thanks so much!

Hi from Spain, i have just the same problem with my hr624, really the best speakers for studio i have had.
My hr624 did the same, it was ON, Off, ON Off..úntil just some days ago did not swich ON more.
I found you in Google, i thought like you jejejeje and im going to try replace the c65 capacitor.
So i give you thank you very much for do public your experience.
I hope much people found the answer to this problem doing this.
King regards.

man you are an idol! i have exactly same proble, now i have to admit soldering scares me a bit, but i will do when speaker go completely dead.Any of you had aslo the issue of having the on off bug when turnin on the volume? mine seems like has to “warm” properly before allowing louder volume

Have run into the same issue with my pair of HR624’s that I’ve had since about 2006.

It started happening very subtly on one monitor… the light flashing on and off and sometimes staying on, but over time (about a month) it would eventually just not turn on at all. After a few weeks of using only one monitor, that one also began to exhibit the same symptoms and now won’t turn on at all either.

Really appreciate your write up on this. Not very competent soldering stuff myself but I will give it a go, worst case scenario they’re already broken 🙂

I had the exact same problem with my pair. One of them kinda revived by itself but the other one was totally dead for years and I kinda gave up on them until I saw your post! I ordered the parts online, received them today and started the fix. I didn’t feel like pulling on the component and went the long road: I have completely disassembled the monitor to access the soldering face of the PCB where I could unsolder the faulty condenser and solder the new one easily enough! It’s now back on my desk and plugged in, working perfectly!
Thank you so much for this page! You basically saved me 1000€ in new active monitors :-).

Sorry but I don’t know if the process would be the same for the H624MK2, but it might well be if the circuit layout is similar. You could open them up and take a look. If you do manage to fix it could you post it it back here? I’ll add it to the article for those with 624s. Thanks!

Thank you so much for sharing this fix. As with many other 624 Mk1,s mine unfortunately started going the same way. Whith the fault the only way I could use them was to basically leave the faulty speaker on 24/7. I,m now pleased to report that with your excellent article I have fixed the fault. Thank you again.

I just replaced C65 on an HK624 MKII and it solved the problem. The cap is in a different spot but it is clearly marked. Local electronics “experts” charged me $65 for their “professional” diagnosis which was replacing the whole board for over 1/2 the price of a new monitor. My eternal gratitude for sharing this with me. Thankyou! Thankyou! Thankyou! 🙂

Funny, now its working if I feed it extremely low level audio. As soon as I turn it up to normal levels (and I listen pretty quietly in my studio) it starts to blink on and off. And even stranger, after I’ve listened to it at low levels for about a minute or two, it is working again.

I was wondering why it was going off and on at such a steady pace… capacitor makes sense.

PS Did I say I’d be happy to pay you for one? Although I do have your specs (63v 4.7uF electrolytic capacitor) does this describe the part in a regular electronics store? I mean do they have some with leads coming out of both ends or is this specification describing the one with two leads coming out of the bottom as your picture?

Well I’m here again to refresh my memory of this fix. I knew it would probably be coming before too long. I fixed one about a year ago so I just knew the other had to fail eventually. Yep, same issue! I just felt the need to send you a hearty thanks and appreciation for your insight and research. These HR624’s really are a wonderful monitor and I’m so very happy that you have provided the world with this fix. Much gratitude to you! -Gabe

On another note, I’ve been purchasing ELNA capacitors for this and other projects. You can find these in many of Tascam, Teac products. They are very good quality and will last for a long time. Just to let you know!

I just wanted to chime in that I made the fix too… according to the instructions. Perfect. Although I took the board out too. Not too much work just 6-8 phillips screws and 4 Allen screws.
Thanks for this blog.

Just a quick message to say a massive thank you. Had exactly this problem, got quotes from a number of repair shops, was looking at £150 minimum. some charge £60 just to take a look at the thing. Thanks to you my speakers are now working perfectly for a 100th of the price. Brilliant!

Same problem here and this fix worked perfectly! I went the long way and removed the PCB to solder the cap from behind the board. I started to regret it after I realized how many screws I had to removed to get to the bowels of the Mac. But after several hours and some gentle persuasion I was able to replace the cap successfully!!
I’ll wait until may other speaker goes out and do the same thing….after all I still have 24 caps left!! Thanks for your post….really really helpful.

One of the two monitors was having problems in the first few years that they were used. After passing a quite firm (but well within the technical specs) audio signal to them, one red light just wouldn’t turn off for days. And now for a year or so the same monitor has the problem you described. It’s a good thing your article is still online, also because Mackie has (re)moved the page that you referred to. After having read your article with its happy responses I decided to give it a try, even when the monitor wasn’t completely ‘dead’ just yet.

To be on the safe side I ordered 10 capacitors online because the shipment cost was about 7 times as high as the cost of the capacitors, making the total repair cost about € 8,=. Also, spare capacitors allow more than one repair attempt which could be useful for whenever the second monitor decides to quit.

To open the back of the monitor an extention for my cordless screwdriver was needed to get to the screws. After having opened the monitor a first attempt failed; the legs of the capacitor were cut somewhat short, and the soldering iron was somewhat large for this task. After turning on essential lighting to get a clear look on the C65 area, and using fingers to hold the new capacitor, my second attempt succeeded and the monitors are shining again. BIG THANKS to your article!

I noticed just now that the green LED of the repaired monitor is much brighter, like a new LED. The green LED of the other monitor is fainter, like the LED is attached to an almost empty battery.
Is this because of the new C65? Anybody has the same experience?

Hello.
just wanted to join the others and congratulate you for this very very helpful tutorial..
ive been searching for information about this for quite some time, this problem started occurring 2 years ago, but then it got fixed by itself, and then returned a few days ago. i decided not to wait and replace the C65.
it worked like a charm! thanks a lot. i did it the same way as you – removing the entire board seems very scary, looks like there obstructing parts that make removing the entire board very difficult..
but im still looking into taking appart everything for the second speaker thatll break eventually… if anyone has a youtube tutorial thatll be great.

Tjeerd Sietsma: yes, my Led also seems to shine brighter than the second untouched monitor.
p.s: ive used a 4.7mF, 100V capacitor, no problems.

Thank you very much for taking the time to inform everyone about this fix. After years of constant and random power ON/OFF’s, they had given their last breath a couple of years ago, yet you resurrected them from the dead for a total of 20 cents and half an hour of soldering, very much appreciated!!

Thnx another pair of MKI are working again…..but looking at the amp pcb and the brand of capacitors Mackie used i would suggest a total recap of that Chinese capacitor lot…especially the two main caps are really bad…..change these for a high grade cap and your bass response will improve. My 2 cents.
But yet again thanks for your site!!!

Woohoo!
My hr624’s are good as new. You are a god. I had one bad and one good, did ’em both. I bought 10 caps have 8 left. If anyone out there needs a couple, email your address. I’ll send you 2. Send me in return 3 Spacebucks. Honor system.telecastic@verizon.net
Thanks a gazillion.
Scott

Wow!
Unbelievable!!
I was SO happy to find this!
I also had one good one and one bad one!
I ordered the capacitors and I was sent the wrong ones..
Then I reordered and received the right ones….or so I thought.
I brought both HR624s..the one that worked, and the one that didn’t, to my local music store to a tech who said it would be a piece of cake to fix them.
Now both of them don’t work.
He’s reordered more capacitors saying he needs ones that have (+) and (-) identifiers on the capacitor in order to know which way to install them….
Does that sound right?

You are my hero. I am absolutely ecstatic. My right HR624 has sat sadly silent for months, and now with a $0.25 part (I had to buy five!) I have restored my stereo sound!
Thank you for making this knowledge available.
-Stuart.

Big help … thanks! Now that I see how many hours these replacement capacitors are rated for (2,000), it’s no wonder I’ve burned through two speakers in 8 years. I keep my power always on and use these as my PC speakers, which I never turn off. Lesson learned. I’m changing to standby mode on the power switch.

Awesome!
Thank you immensely for taking the time and trouble of posting the fix and photos.
I concluded the repair of C65 and all of the other caps(preemptive precaution)utilizing
the best Rubycon caps.
My speakers are alive again!
To have knowledge is great even better is to share it and assist your fellow man…….bravo, SIR !

And as you so eloquently stated: now it’s Sitt’n time………………pop open a beer and listen to some righteous tunes.

Well it’s been almost exactly 3 years since I wrote this post, and now my left side HR624 is failing in exactly the same way. Hmmm….were did I put that extra capacitor. Might have to sit and ponder that a bit before diving into the repair.

Thanks it worked on my Mackie HR624 i found a old board off something else and remove a 4.7uf 400v capacitor it is bigger in size, but solder some wire legs on it installed and worked great ! Had it fix the same day i found your info. Thanks i now have my fine Mackie HR624 High Resolution Studio Monitors working great. I will order from Amazon the 4.7uf 63v Capacitor just incase the other go out. Thanks.

The links to the caps on Amazon are for non-polarized capacitors. Has anyone actually used these? I ordered them, but not want to try them if it truly requires polarized caps. I googled non-polar vs. polarized and seems it shouldn’t matter, but I don’t want to blow anything in my HR624s if I should just order the polarized versions and wait another couple of days.

I was so chuffed to find this page, but sadly it wasn’t the issue with my duff HR624. There are 2 x 800mA internal fuses that protect the transformer, and one of these had blown. A replacement blew straight away, even with the transformer secondary disconnected from the PCB, so I checked the resistances across the coils – it measured 55 ohms between the 2 primary windings (between yellow/red & black), and about 15 ohms across each winding. I wasn’t sure if this was normal, until I eventually realised that stereo means I had another to compare with! Sure enough, the transformer in the working speaker measures infinite resistance between the two primary windings suggesting the transformer is dead, presumably with a short blowing the fuse each time. Putting the good transformer in got the speaker working again, so I’m now on the hunt for a replacement transformer.
To answer the question above, my understanding is that non-polarised caps are fine in this situation, it’s just harder to find them at this value – polarised are cheaper & smaller, though farnell in the UK had some 4.7uF film caps quite cheap – order code 1006056. Although I don’t think I’ll need to swap C65 yet, I’d probably use these instead of an electrolytic, to save doing it again in 10 years! It is easy to take the whole assembly out & would make the cap fix easier – some screws at the back & 4 tiny star type Allen keys is all.

Loved my Mackie H624 speakers but had not used my studio set up in several years. Spent the day rewiring everything and just got done only to find that the only thing that did not turn on is the pair of Mackies. Truly disappointing. But glad I found your page and try out what seems to have worked for so many. My thanks anyway in advance assuming I’ll get to doing the repair in the next 8 years considering my To Do list going back to 1989. LOL.

Just to update – it works, never been so pleased to see a green LED come back on.
Wiring for the CM0120230 Airlink transformer is below, but transformers vary so don’t rely on this if it’s not the same model. Best to test you’re getting around 30v AC on the outs before connecting the secondary to the PCB.
1mry: transformer blue -> yellow PCB connector, grey -> black PCB, violet -> yellow / red PCB, brown -> black / red PCB
2nry: red -> 1 brown PCB, yellow -> other brown, orange & black both connect to brown with yellow stripe PCB (ground).
green & yellow -> chassis earth.

Another year on and this thread is still delivering the goods! I had exactly the same problems as Si (cheapo Chinese transformers Mackie?) and replaced it with the Airlink CM0120230 as per Si’s post. All good so far, so a huge thanks to Si from me.

Also curious if non-polarized caps will work and from what I’ve read they should be fine. As I understand it, non-polarized are more expensive than a polarized cap because they are two polarized caps together. No one responded to Sean because maybe it’s obvious to most but will give them a try in a week or so and respond back.

Thanks so much for this. I was hoping to send my monitor off to the ‘approved repairer’ here in the UK (£100 just for taking the cover off) once I had the money, but this information saved me the cost…. £1.49 delivered for 10 capacitors and about half an hour and it’s back from the dead.

Not sure if anyone is still reading this, but it’s worth a shot. So, I thought that I had the same problem, but replacing C65 didn’t correct the issue, and I actually have both 800mA fuses blowing. I then thought, like Si, that maybe the transformer was bad. After some testing though, I don’t think that’s the issue. The fuses ONLY blow when the transformer secondary is connected to the PCB. I took voltage readings at the secondary without it connected and I was getting 33VAC across brown and brown/yellow (66VAC across brown and brown). Also, input resistance is infinite on the primary. Could the transformer still be the problem? (I haven’t gone down the road of trying it with the one from the working speaker) Is there something in the transformer circuit (downstream of the secondary) that could be causing the problem? What short would be blowing both fuses?

I pulled the board and replaced c65. Presto! It worked. Removing the board requires 4 screws on the board and 2 screws from the sides. There are 2 nylon snap fit retainers that poke up into two holes in the board

Thank you so much. I was stumped as to why my HR624’s were not working. I tried your method and screwed up a bit as I am a brute who has never soldered. However, my neighbor inquired what I was up to, I told him that I needed to do some desoldering. He told me to bring the monitor over to his garage. 30 minutes later, BOTH monitors have new capacitors and I am in bliss with that awesome sound flowing through my eardrums!!! Thank you once again!! DJ P Rock.

Help please. I changed out the capacitor and it didn’t work. Turned out to be that 1 of the 2 fuses was blown (checked 1 and missed the other). Changed the fuse out it worked but when i put it all back together and tested, got a horrible scratchy / radio static sound out of the speaker (like it was a radio tuned between stations). Resoldered, same. Swapped out for a new cap, then nothing, wouldn’t even switch on. Checked all the fuses, even the mains. I’m so mad at myself for not having seen the 2nd fuse and now i’m at a complete loss. Why won’t the speaker power up? 🙁

Someone PLEASE tell me what power cord I need for these speakers? I’ve been searching forever. It’s the two pin one. I got a pair of these monitors really cheap from my local music store and assumed it would have the normal 3 prong plug. . It’s some weird 2 pin deal. The music store had a couple of two pin plugs but they didn’t fit HELP!! lol

the cord isnt special, its just missing the third plug for ground. you can use a standard power cable for a computer, it wont cause any problem at all. the additional ground is just not used on the 624/626 (which makes it a bit more like consumer audio equipment that way)
but yes i have been using a 3-pin computer cable for years and it works perfectly fine

Thanks for posting this fix… I just fixed one of two dead mackies HR624 today. Sadly to find both my drivers blown – anybody have one?

AN ODE TO C65
Oh blue cylinder
small and vulnerable
yet with a powerful role
unable to hold charge any more
so the chip amps sleep
you have withered and died
so I pluck you out and replace you afresh
LEDs light and sounds reward
oh little cap you betrayed me

Wow. Thank you for writing this, and thanks to all the commenters providing insight to what works (in my case I have a HR626 to repair). Over 5 years later, this article is invaluable, and I can only imagine it will continue to be as these speakers gets older.